feat: 添加文件差异对比工具及测试文件

- 新增 test_diff_tool.go 实现文件差异对比功能
- 添加测试文件 test_file_a.txt、test_file_b.txt 和 test_file_whitespace.txt
- 删除旧的 .picoclaw.pid 文件
- 更新 logs/gateway.log 日志文件

.picoclaw.pid

@@ -1,7 +0,0 @@
-{
-  "pid": 7160,
-  "token": "ca0cf39c3f6188acfa724839d8382f1a",
-  "version": "dev",
-  "port": 18790,
-  "host": "localhost"
-}

logs/gateway.log

@@ -115,3 +115,12 @@
 {"level":"debug","component":"heartbeat","time":"2026-04-18T01:43:43+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/heartbeat/service.go:163","message":"Executing heartbeat"}
 {"level":"info","component":"heartbeat","time":"2026-04-18T01:43:43+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/heartbeat/service.go:167","message":"No heartbeat prompt (HEARTBEAT.md empty or missing)"}
 {"level":"error","component":"gateway","config_path":"d:\\Desktop\\一面千石\\picoclaw\\config.json","error":"error opening gateway listeners: failed to open adaptive localhost listener on port 18790","home_path":"d:\\Desktop\\一面千石\\picoclaw","allow_empty":false,"debug":true,"time":"2026-04-18T01:44:16+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/gateway/gateway.go:137","message":"Gateway startup failed"}
+{"level":"info","component":"gateway","time":"2026-04-18T01:49:32+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/gateway/gateway.go:265","message":"Shutting down..."}
+{"level":"info","component":"channels","time":"2026-04-18T01:49:32+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/channels/manager.go:672","message":"Stopping all channels"}
+{"level":"info","component":"channels","time":"2026-04-18T01:49:32+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/channels/manager.go:729","message":"All channels stopped"}
+{"level":"info","component":"channels","time":"2026-04-18T01:49:32+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/channels/manager.go:889","message":"Outbound media dispatcher stopped"}
+{"level":"info","component":"channels","time":"2026-04-18T01:49:32+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/channels/manager.go:889","message":"Outbound dispatcher stopped"}
+{"level":"info","component":"devices","time":"2026-04-18T01:49:32+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/devices/service.go:96","message":"Device event service stopped"}
+{"level":"info","component":"heartbeat","time":"2026-04-18T01:49:32+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/heartbeat/service.go:116","message":"Stopping heartbeat service"}
+{"level":"info","component":"gateway","time":"2026-04-18T01:49:32+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/gateway/gateway.go:509","message":"✓ Gateway stopped"}
+{"level":"info","component":"pid","time":"2026-04-18T01:49:32+08:00","caller":"D:/Desktop/一面千石/picoclaw/pkg/pid/pidfile.go:150","message":"remove pid file: d:\\Desktop\\一面千石\\picoclaw\\.picoclaw.pid"}

test_diff_tool.go

@@ -0,0 +1,84 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"github.com/sipeed/picoclaw/pkg/tools"
+)
+
+func main() {
+	workspace, _ := os.Getwd()
+	maxReadFileSize := 64 * 1024
+
+	fmt.Println("=== 测试 diff_files 工具 ===\n")
+
+	tool := tools.NewDiffTool(workspace, false, maxReadFileSize)
+
+	fmt.Printf("工具名称: %s\n", tool.Name())
+	fmt.Printf("工具描述: %s\n", tool.Description())
+	fmt.Println()
+
+	testUnifiedDiff(tool)
+	testSideBySideDiff(tool)
+	testIgnoreWhitespace(tool)
+
+	fmt.Println("\n=== 测试完成 ===")
+}
+
+func testUnifiedDiff(tool *tools.DiffTool) {
+	fmt.Println("--- 测试 1: 统一差异格式 (unified diff) ---")
+	fmt.Println()
+
+	args := map[string]any{
+		"file_a":        "test_file_a.txt",
+		"file_b":        "test_file_b.txt",
+		"format":        "unified",
+		"context_lines": 3,
+	}
+
+	result := tool.Execute(context.Background(), args)
+	fmt.Println("结果:")
+	fmt.Println(result.ForLLM)
+	fmt.Println()
+}
+
+func testSideBySideDiff(tool *tools.DiffTool) {
+	fmt.Println("--- 测试 2: 并排对比格式 (side_by_side) ---")
+	fmt.Println()
+
+	args := map[string]any{
+		"file_a": "test_file_a.txt",
+		"file_b": "test_file_b.txt",
+		"format": "side_by_side",
+	}
+
+	result := tool.Execute(context.Background(), args)
+	fmt.Println("结果:")
+	fmt.Println(result.ForLLM)
+	fmt.Println()
+}
+
+func testIgnoreWhitespace(tool *tools.DiffTool) {
+	fmt.Println("--- 测试 3: 忽略空白字符差异 (ignore_whitespace) ---")
+	fmt.Println()
+
+	args := map[string]any{
+		"file_a":            "test_file_a.txt",
+		"file_b":            "test_file_whitespace.txt",
+		"format":            "unified",
+		"ignore_whitespace": false,
+	}
+
+	fmt.Println("不忽略空白差异:")
+	result1 := tool.Execute(context.Background(), args)
+	fmt.Println(result1.ForLLM)
+	fmt.Println()
+
+	args["ignore_whitespace"] = true
+	fmt.Println("忽略空白差异:")
+	result2 := tool.Execute(context.Background(), args)
+	fmt.Println(result2.ForLLM)
+	fmt.Println()
+}

test_file_a.txt

@@ -0,0 +1,11 @@
+# 示例文件 A - 原始版本
+这是一个用于测试文件差异对比功能的示例文件。
+
+## 功能列表
+- 支持统一差异格式
+- 支持并排对比格式
+- 支持忽略空白字符差异
+
+## 注意事项
+请确保文件编码为 UTF-8。
+大文件可能需要较长时间处理。

test_file_b.txt

@@ -0,0 +1,16 @@
+# 示例文件 B - 修改版本
+这是一个用于测试文件差异对比功能的示例文件。
+新增的一行内容。
+
+## 功能列表
+- 支持统一差异格式
+- 支持并排对比格式
+- 支持忽略空白字符差异
+- 新增：支持彩色输出（新增功能）
+
+## 注意事项
+请确保文件编码为 UTF-8。
+大文件可能需要较长时间处理。
+
+## 更新日志
+- 2026-04-18: 新增功能说明

test_file_whitespace.txt

@@ -0,0 +1,11 @@
+#  示例文件 A - 原始版本
+这是一个用于测试文件差异对比功能的示例文件。
+
+##  功能列表
+- 支持统一差异格式
+- 支持并排对比格式  
+- 支持忽略空白字符差异
+
+##  注意事项
+请确保文件编码为 UTF-8。
+大文件可能需要较长时间处理。